In various conventional thin film deposition methods, a method of depositing a buffer layer of a superconducting sheet is performed through a sputtering process, an evaporation process or an electron beam deposition process. However, such a method of depositing a buffer layer of a superconducting sheet is problematic in that processes of depositing a thin film must be repeatedly conducted in order to form a multi-layered thin film, and thus additional costs for establishing a system for conducting the processes and maintaining the system are incurred, and it is difficult to decrease the manufacturing time of a superconducting sheet and to secure economic efficiency because the number of the processes for depositing a thin film is increased.
For instance, a REBCO (for example, YBCO, SmBCO, GdBCO or NdBCO) based superconducting sheet, which is a typical second-generation superconducting sheet, must have a multi-layered buffer thin film (for example, Y2O3/YSZ/CeO2, CeO2/YSZ/CeO2, etc.) deposited thereon. Therefore, in order to form such a multi-layered buffer thin film, deposition apparatuses, such as a sputterer, an evaporator and an electron beam laser, are sequentially operated depending on the number of components (Y2O3, YSZ, and CeO2) constituting the multi-layered buffer thin film.
The multi-layered buffer thin film formed above is problematic in that processes of depositing a thin film are conducted several times and deposition conditions must be differently set for each of the processes, and thus productivity is decreased and costs are increased in the manufacturing of a superconducting sheet, thereby decreasing economic efficiency.
Further, the multi-layered buffer thin film is problematic in that the difference in the physical properties between buffer thin films causes various problems, and it cannot properly serve as a buffer layer between a substrate and a superconductor because it is difficult to control the processes of depositing a buffer layer, which are conducted to set all of the characteristics of a superconducting sheet.